John tjbban mcdowald



I. U McDONALD.

FURNACE.

APPLICATION FILED SEPT. 7, 1920.

Patented Mar. 1, 1921.

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ICE.

1 JOENURBAN MoDONALD, or DECATUR, ILLINOIS.

FURNACE.

Specification of Letters Patent.

Patented llfar. 1, 1921.

i Application filed September 7, 1920. Serial No. 408,632.

To all to from it may concern: 1

Be it known that I, JOHN URBAN McDonnLo,'a citizen of the United States, and residing at Decatur, in the county of Macon and State of Illinois, have invented a new and Improved Furnace, of which the following is a specification.

This invention relates to that class of furnaces in which metals are melted in pots or crucibles and its object is to provide a furnace of maximum efliciency for the fuel consumed and which is'especially adapted for the use of powdered coal as a fuel.

This invention consists of a furnace having a front wall extending upwardly to an arch provided with holes to permit the es- "cape of the products of combustion, a reartion chamber, the rear wall of the combustion chamber being constituted by two concave surfaces, preferably cylindrical.

It also consists in providing apertures in the roof of the combustion chamber so that the crucibles may be lowered down onto the floor of said chamber and spaced apart from the walls and from each other to permit the incandescent fuel and products of combustion to pass between the crucibles until the rear wall is reached and then rebound and pass forward around the crucibles to the front arch where they pass upward through the openings therein.

It further consists in the details of con,- struction illustrated in the accompanying drawing and particularly pointed out in the claims.

In the accompanying drawing, Figure 1 is a vertical central longitudinal section of this improved furnace. Figs. 2 and 3 are sections on the lines 22 and 33 of Fig. 1 respectively.

Similar reference characters refer to like parts throughout the several views.

The furnace shown in the drawing has side walls 1, a rear wall 2, a bottom 3 sloping down forwardly to the ash pit 4, and an arched. roof 5 which preferably slopes up from the rear wall 2 to the front arch 6. The roof 5 has openings 7 to admit the crucibles 8, which'holes have covers 9. I prefer to form low pedestals 10 for the crucibles, the height of these pedestals being determined by the pressure of the fuel feed and the character of the fuel. Deflectors 12 are built out from the walls 1 and the inner sur face of the rear wall is in the form of two half cylinders 13, divided by a deflector 14.

The powdered coal is forced through the pipe 15 into the furnace, preferably by means of highly heated air, the source of theair and coal not being shown. Because of this initial heat, the fuel burns at substantially the instant it leaves the pipe 15 with a very hot clear blue-white flame. The ash in the coal melts at once and flows down into the ash pit l.

The intensely hot products of combustion pass to the rear end of the furnace where they are split by the ridge 14:, substantially one half passing around each rear crucible 8 and then forward around the forward crucibles, rising in the meantime and being turned inwardly toward the pipe 15 by means of the deflectors 12. These gases then finally pass outwardly through the holes 16 in the arch 6. The heat carried away being utilized in any desired manner, preheating another furnace preferred.

The pedestals 1O elevate the crucibles from the floor into the zones of more intense heat. The fuel is ignite-d at the inner end of the pipe 15 and is burned almost completely by the time it reaches the forward crucibles, which are therefore subjected to intense heat on their inner sides, but the temperature of the products of combustion is still very high on the outsides of the forward crucibles.

The proportions and details of this furnace may all be changed by those skilled in the art without departing from the spirit of my invention as set forth in the following claims.

I claim 1. In a furnace, a bottom sloping downwardly toward the front, a front wall, side walls, an arched top provided with holes to admit crucibles, a fuel pipe extending through the front wall, and a rear wall provided with a forwardly extending ridge to cause the products of combustion to divide and one-half to pass forwardly along each side wall.

2. In a furnace, a bottom sloping downwardly toward the front, a front wall, side walls, an arched top provided with holes to admit crucibles, a fuel pipe extending through the front wall, and a rear wall provided with a forwardly extending ridge to cause the products of combustion to divide and one-half to pass forwardly along each side Wall, the rear wall being concave between theridge and each side wall.

3. In a furnace, a bottom sloping downwardly toward the front, a front wall, side with pedestals to support crucibles which are spaced from the side wall and the top being formed with openings to admit the crucibles.

4C. In a furnace, a bottom sloping downwardly toward the front, a front wall, side walls, an arched top, a fuel pipe extending through the front wall, and a rear wall provided with a forwardly extending ridge to cause the products of combustion to divide and one-half to pass forwardly along each sidewall, the bottom being formed with pedestals to support crucibles which are spaced from the'side wall and the top being formedwith openings to admit the crucibles, said side walls being formed with inwardly extending deflectors between the front crucibles and the front wall to cause the products of combustion to flow around the front crucibles.

In a furnace having a bottom, a top, side, front and back walls, said top having openings to admit crucibles which are spaced from the side walls, a fuel pipe extending throughthe front wall-to direct fuel centrally of the furnace toward the back wall between that the products of combustion will pass between the side walls and the adjacent crucibles.

6. In a furnace, at front arch having open ings in its crown to permit the escape of the products of combustion, a front wall, an ash pit below said arch, a heating chamber in the rear of said arch and ash pit and 00111- prising side walls, an arched top, a bottom and a rear end wall, said top sloping down toward the rear and the bottom sloping down toward the front, and the rear end wall being formed with a central vertical deflector and with a concave surface on each side to direct the products of combustion toward the front wall.

7. In a furnace, a bottom, a front wall, side walls, a top, a fuel pipe extending through the front wall, and a rear wall provided with a forwardly extending ridge to cause the products of combustion to divide and to pass forwardly along each side wall.

JOHN URBAN MCDONALD. 

